Calendar Name: seminars
Scheduled for: Monday, July 2 2012, 11:00 - 12:30
Event text: Dr Javier Palatnik
IBR
(Instituto de Biologia Molecuar y Celular de Rosario)
Rosario
ARGENTINA
Details: �microRNA biogenesis and function in plants�
ABSTRACT
MicroRNAs are small RNAs of ~21 nt that recognize
partially complementary sites in target mRNAs and guide
them to cleavage or translational arrest. The microRNAs
are distinguished from other small RNAs by their unique
biogenesis, which involves a precise excision from the
stem of a fold-back precursor located in a long primary
transcript. The type III ribonuclease DICER-LIKE1 (DCL1)
with the aid of the accessory proteins cleaves the
precursors to release the microRNAs. However, plant
microRNA precursors come in variable sizes and shapes,
and we are interested in understanding how these
different precursors can be processed to generate the
mature microRNAs.
We have found that many precursors are processed in a
base-to-loop direction, while others are processed by a
non-canonical loop-to-base mechanism. We use a
combination of approaches to study microRNA processing,
including the analysis of libraries of random mutant
precursors and the identification of processing
intermediates with the aid of next generation sequencing
techniques.
In plants, many of the evolutionary conserved miRNAs
regulate transcription factors, which in turn play key
biological functions. Perturbation of these miRNA
regulatory networks, by mutations in microRNA encoding
genes or by interference with their activity usually
causes severe developmental defects. We are interested
in identifying the targets of plant microRNAs, as well
as their biological functions. The lab specifically
focuses in the control of cell proliferation and
differentiation by two microRNAs, miR396 and miR319.
Related Publications:
Bologna, N.G., Mateos, J., Bresso, E.G., and Palatnik,
J.F.. (2009) A loop-to-base processing mechanism
underlies the biogenesis of plant microRNAs miR319 and
miR159. EMBO J, 28:3646-56.
Mateos, J., Bologna, N.G., Chorostecki, U., and
Palatnik, J.F. (2010) Identification of Structural
Determinants for MicroRNA Processing in Plants by Random
Mutagenesis of MIR172a Precursor. Current Biology,
20:49-54.
Rodriguez, R., Mecchia, M., Debernardi, J.M., Schommer,
C., Weigel, D., and Palatnik, J.F. (2010) Control of
cell proliferation by microRNA miR396. Development,
137:103-12.
Debernardi, J.M., Rodriguez, R.E., Mecchia, M., and
Palatnik, J.F. (2012) Functional specialization of the
plant miR396 regulatory network through distinct
microRNA-target interactions, PLoS Genetics, 8:
e1002419.
Chorostecki, U., Crosa, V.C., Lodeyro, A.F., Bologna,
N.G., Martin, A.P., Carrillo, C., Schommer, C. and
Palatnik, J.F. (2012) Identification of new
microRNA-regulated genes by conserved targeting in plant
species, in press.
